Various tests have been developed to ensure that concrete used in particular applications satisfy specifications. One of these is a compression test for testing concrete cylinders. The concrete cylinder is typically formed using a test cylinder mold. The mold is a hollow cylindrical container including a bottom wall used to test specimens of concrete at a construction site. Such molds are generally disposable.
Particularly, samples of concrete are routinely acquired from job site projects for laboratory testing to verify and certify the strength of the concrete used in a specific project. The specimens are collected, according to strict ASTM guidelines, in plastic containers or wax impregnated paper cylinders, commonly referred to as concrete test cylinder molds. The test cylinder molds are offered in different sizes, such as 6 inch diameter by 12 inches high, 4 inch diameter by 8 inches high, 3 inch diameter by 6 inches high, and 2 inch diameter by 4 inches high.
Initially, such molds were made of paper board with metal bottoms. More recently, the molds are injection molded from polypropylene which is recyclable.
Reprocessors/recyclers of plastics need to know the composition of the plastic in order to sell it in the plastic material after market. For example, plastic items molded for use in the food and medical market must be molded from “virgin” material. Scrap from these processes are sold to reprocessors since the molder cannot reuse. The reprocessor knows the exact composition of the plastic material purchased from the molder and can offer it in the after market.
In a consumer recycling program, plastic items are collected in bins by the local waste company and taken to a sorting point where the recyclable materials are separated. However, there are thousands of different grades of polypropylene. The grade used for typical test cylinder molds is a copolymer, 8-10 melt, 2.5-2.7 izod material. Polypropylenes which are homo polymers have higher or lower melts, or are of different izods and cannot be used. Since the recycle symbol does not distinguish the differences in the polypropylene grades, it is doubtful the test cylinder mold material would be accepted by a reprocessor for the material after market. As a result, the molds often end up in a landfill.
Testing laboratories would be in the industrial waste management market. They would use a 20-40 cubic foot container. The plastic test cylinders would be removed from the concrete specimens and thrown into the waste container, along with the broken concrete specimens as a result of the destructive testing. As a result, most test cylinder molds wind up in landfill and can contribute to environmental problems.
In accordance with the invention, a test cylinder mold is injection molded from a biodegradable material.